fix: Handle App objects in eval and graph endpoints

Merge #3060 ## Description Fixes #3059 This PR fixes two endpoints in `adk web` that fail when using App objects instead of bare agents. ## Changes - **Eval execution endpoint** (line ~969): Extract root_agent from App objects before passing to LocalEvalService - **Graph visualization endpoint** (line ~1308): Extract root_agent from App objects before graph operations Both endpoints now properly handle both BaseAgent and App objects by checking the type and extracting `.root_agent` when needed. ## Testing Plan ### Manual E2E Testing with ADK Web Tested with an App object that includes context caching: ```python from google.adk.apps import App from google.adk.agents import LlmAgent root_agent = LlmAgent(name="MyAgent", model="gemini-1.5-pro-002") app = App( name="my_agent", root_agent=root_agent, context_cache_config=ContextCacheConfig(...) ) ``` **Before fix:** - Graph visualization failed (tried to call agent methods on App object) - Eval execution failed (LocalEvalService received App instead of agent) **After fix:** - Graph visualization works correctly - Eval execution works correctly - Both endpoints properly extract root_agent from App objects ## Checklist - [x] Code follows project style (autoformat.sh passed) - [x] Changes are focused and minimal - [x] Issue #3059 created and referenced - [x] Manual E2E testing completed COPYBARA_INTEGRATE_REVIEW=#3060 from ejfn:ejfn/bugfix-app-object-endpoints 01c3019 PiperOrigin-RevId: 821746910

Author: ejfn

src/google/adk/cli/adk_web_server.py

@@ -486,6 +486,12 @@ async def get_runner_async(self, app_name: str) -> Runner:
  self.runner_dict[app_name] = runner
  return runner
 
+ def _get_root_agent(self, agent_or_app: BaseAgent | App) -> BaseAgent:
+ """Extract root agent from either a BaseAgent or App object."""
+ if isinstance(agent_or_app, App):
+ return agent_or_app.root_agent
+ return agent_or_app
+
  def _create_runner(self, agentic_app: App) -> Runner:
  """Create a runner with common services."""
  return Runner(
@@ -933,9 +939,8 @@ async def add_session_to_eval_set(
 
  # Populate the session with initial session state.
  agent_or_app = self.agent_loader.load_agent(app_name)
- if isinstance(agent_or_app, App):
- agent_or_app = agent_or_app.root_agent
- initial_session_state = create_empty_state(agent_or_app)
+ root_agent = self._get_root_agent(agent_or_app)
+ initial_session_state = create_empty_state(root_agent)
 
  new_eval_case = EvalCase(
  eval_id=req.eval_id,
@@ -1096,7 +1101,8 @@ async def run_eval(
  status_code=400, detail=f"Eval set `{eval_set_id}` not found."
  )
 
- root_agent = self.agent_loader.load_agent(app_name)
+ agent_or_app = self.agent_loader.load_agent(app_name)
+ root_agent = self._get_root_agent(agent_or_app)
 
  eval_case_results = []
 
@@ -1437,13 +1443,7 @@ async def get_event_graph(
  function_calls = event.get_function_calls()
  function_responses = event.get_function_responses()
  agent_or_app = self.agent_loader.load_agent(app_name)
- # The loader may return an App; unwrap to its root agent so the graph builder
- # receives a BaseAgent instance.
- root_agent = (
- agent_or_app.root_agent
- if isinstance(agent_or_app, App)
- else agent_or_app
- )
+ root_agent = self._get_root_agent(agent_or_app)
  dot_graph = None
  if function_calls:
  function_call_highlights = []